TW202124930A - Pressure gauge capable of release pressure safely - Google Patents

Abstract

A pressure gauge is movably connected with an air compressor and moves like a piston so as to display a pressure value. The pressure gauge contains at least one discharge orifice and a pressure protection unit. When the pressure gauge measures the pressure value reaches a set safe value, the pressure is discharged out of the at least one discharge orifice. When the pressure value reaches a maximum safe value, the pressure is discharged out of the at least one discharge orifice and the pressure protection unit, thus obtaining a safety to the air compressor without using a safety value and to an inflatable object.

Description

Pressure gauge with multi-stage safety relief

The present invention provides a pressure gauge with multi-stage safety pressure relief, in particular to an air compressor that can be movably combined with a pressure gauge and the pressure gauge can generate a piston-like movement for pressure display. The pressure gauge is also designed There is at least one vent hole and an overpressure protection unit, which can be measured by the installed pressure gauge to measure the current pressure value change, and when the pressure value reaches the set safe pressure value, at least one vent hole will discharge the excess When the pressure value reaches the set maximum safety pressure value, the vent hole and overpressure protection unit on the pressure gauge will release the excess pressure at the same time, so that the air compressor can achieve safety without additional safety valve. Benefit, will not cause overpressure damage to inflatable items.

Early air compressors, especially small air compressors used in the inflation of automobile tires, air cushions, etc., were equipped with only two ducts and one duct on the air storage seat. The tube is used to install a round box-shaped pressure indicator, and the other manifold is used to connect a hose with an air nozzle at one end, which is connected to the object to be inflated, such as a car tire, operated by an air compressor The generated compressed air is delivered to the object to be inflated to achieve the purpose of inflating, and the pressure indicator can provide the user with the current pressure value visually, as a basis for the safety of controlling the inflation action; this conventional round box shape The pressure indicator is a mechanical pointer pressure gauge made using the principle of Burden Tube. Because this type of Burden tube pressure indicator requires more precision components, it uses precision The components are also prone to damage, resulting in loss of accuracy during measurement; therefore, the use of the Baden tube pressure indicator is not effective. In order to overcome the lack of the use of the Baden tube pressure indicator, a utility model of a pressure indicator device for an inflator is currently disclosed in the Japanese Patent Gazette. Japan Utility Model Registration No. 3185073 (U3185073). It has a hollow tube body with a sheath and an air inlet connector at the two ends of the tube body. The tube body is provided with a flat plate body and a spring that can move linearly in the tube body. There is a ruler. The most characteristic feature of the tube is a pressure relief hole. When the push block receives the compressed air from the inflator, the flat plate can compress the spring and move linearly. When the inflation pressure exceeds the maximum When the pressure is set, the pressure relief hole provided in the hollow tube body will release the excess pressure to protect the inflation safety of the inflated object; this known public creation has a breakthrough in the structural design, although it has broken through the conventional Baden tube type Pressure indicator, but because the area of the pressure relief hole used as an overpressure safety protection is too narrow, it is a point-shaped round hole. Since the inflation speed of the inflator is quite fast, the pressure relief hole instantly vents The performance of the pressure is not good. On the other hand, the pressure relief hole is easily blocked by the circulating dirt and dust and the dust mixed with the lubricating oil used to increase the smooth operation of the inflator body, which may reduce or lose the pressure relief. On the other hand, it is worth noting that one end of the strip flat plate is movably connected to the groove of the push block sleeve, and the other end passes through the perforation in the center of the sheath. When the push block and the spring are shared Under the influence of the high-frequency vibration of the inflator, the end of the plane plate connected with the push block is more likely to loosen and deviate. This will cause the other end of the plane plate to form a skewed displacement movement. The moving path will increase the friction between the four perimeters of the plate and the perforation in the sheath perforation, and it is easy to wear the perforation wall and expand the perforation area, and the perforation that is worn and enlarged will cause The shaking and vibration of the flat panel body can easily cause the flat panel body and the push block to loosen or completely fall off, so that there will be obstacles or loss of accuracy in the pressure measurement; on the other hand, the straight line of the panel body The length of the displacement plus the structural length of the ruler will also increase the length obstacle of the entire display device in terms of space design, which is also an area to be considered for improvement. The inventor feels that the conventional pressure gauge still has a lack of use, and actively develops and improves it. Today, he has developed a multi-stage pressure relief pressure gauge, especially an air compressor that can be combined with a movable type. Pressure gauge and the pressure gauge can produce pressure display in a manner similar to the movement of a piston. The pressure gauge is also equipped with at least one vent hole and an overpressure protection unit. The current pressure value can be measured by the installed pressure gauge In addition to changes, when the pressure value reaches the set safety pressure value, at least one vent will release the excess pressure, and when the pressure value reaches the set maximum safety pressure value, the pressure gauge is provided with a vent hole and overpressure protection The unit will release the excess pressure at the same time, so that the air compressor can achieve safety benefits without additional safety valves, and will not cause overpressure damage to the inflated items.

The main purpose of the present invention is to provide a pressure gauge with multi-stage safety pressure relief. The manifold set on the air cylinder of the air compressor can be directly connected to a pressure gauge with an overpressure protection unit. The pressure gauge It is also equipped with at least one vent hole and an overpressure protection unit, which can be measured by the installed pressure gauge to measure the current pressure value change, and when the pressure value reaches the set safe pressure value, at least one vent hole will vent Release the excess pressure, and when the pressure value reaches the set maximum safety pressure value, the vent hole and the overpressure protection unit provided on the pressure gauge will release the excess pressure at the same time, without the need for another outlet manifold on the air compressor Pressure safety valve is installed inside.

In order for the examiner to understand the specific structure of the present invention in more detail, please refer to the first to fourth figures. The present invention provides a pressure gauge 10 with multi-stage safety pressure relief. The pressure gauge 10 can be combined with an air compressor. 9 is connected, where the pressure gauge 10 includes a hollow round tube body 1, the hollow round tube body 1 is a transparent cylinder with an inner chamber 11, one end is an open end 12 and is provided with a male thread 121, and the other end is The tail end 13 is provided with a pair of inserting clamp bodies 131, and the outer center of the tail end 13 is additionally provided with a connecting head 14 which has an inner channel 140 communicating with the inner chamber 11 of the circular tube body 1, and is mounted on the connecting head 14 Two separated airtight O-rings 15 and 16 are provided. On the outer side of the circular tube body 1 near the tail end 13, a display unit 17 combined with a numerically depicted pressure value is provided. The inner side of the display unit 17 is connected to the circular tube The body 1 is combined in a separate manner to form a pressure gauge 10. The circular tube body 1 is formed in the inner chamber 11 with two left section 111 and right section 112 of different circular calibers, as shown in the direction and Taking the central axis C of the circular tube body 1 as a reference, there is a left section 111 with a radius X near the inner passage 140, and a right section 112 with a radius Y near the open end 12, with a radius X Less than the radius Y (X>Y), at the end of the left section 111 and the right section 112 adjacent to each other, a radial shape with a slope (relative to the central axis) is formed inside the circular tube body 1. C) The ring segment 113, in this embodiment, is the radius X of the left segment 111 with a small diameter, which extends to the radius Y of the right segment 112, the left segment 111 and the right segment in a manner of continuously increasing diameter. A radial ring segment 113 is formed between the two 112. The circumferential surface of the ring segment 113 (still in the view direction of the fourth figure) can be linear or arc-shaped. , The outer cylinder wall of the circular tube body 1 near the left section 111 of the ring section 113 is provided with a first vent hole 18, and the outer cylinder wall of the circular tube body 1 near the right section 112 of the ring section 113 A second vent 19 is provided (refer to Figures 4 and 7 at the same time).

A propeller 2 can be placed in the aforementioned circular tube body 1. When the compressed air generated by the air compressor 9 enters the aforementioned circular tube body 1, it can not only push the propeller 2 for linear displacement, but also The current pressure value is indicated by the moving length of the propeller 2, as shown in the sixth figure. Please refer to the third and fifth figures. In the pusher 2 in the embodiment of the present invention, the pusher 2 has an open end 21 at one end, and the other end of the pusher 2 is a bottom end seat 22, the outer side of the bottom end seat 22 The plane is provided with a recessed groove 221, and the thruster 2 has an inner hollow portion 23, and the bottom end seat 22 extends at the center of the bottom of the inner hollow portion 23 and a hollow tube 24 extending through the open end 21 , And inside the hollow tube 24 of the bottom end seat 22 is provided a convex wall 25 with an exhaust passage 250, that is, the groove 221 outside the bottom end seat 22, the exhaust passage 250 and the hollow tube 24 are in a connected state , And a ring recess 26 is formed between the bottom of the hollow tube 24 and the cylinder wall of the pusher 2; a ring recess 27 is provided on the peripheral side of the aforementioned bottom end seat 22, and a colored O-ring 28 can be sleeved in it. An overpressure protection unit, the overpressure protection unit in the embodiment of the present invention is an exhaust valve 3, which is provided with an outer end 31, and a vertical rod 32 extends from the other end of the outer end 31, the The end of the vertical rod 32 is provided with two opposite side wings 33; a leak-proof spring 34, which can be placed in the hollow tube 24 of the propeller 2, and one end of the leak-proof spring 34 is attached to the convex wall 25; The side wing 33 end of the air valve 3 is penetrated into the exhaust passage 250 and the anti-leak spring 34 from the groove 221 outside the bottom end seat 22 of the propeller 2, and the side wing 33 of the exhaust valve 3 is hooked to the anti-leak spring 34 The other end, and the outer end 31 of the exhaust valve 3 is seated in the groove 221 outside the bottom seat 22 of the thruster 2. At this time, the anti-leak spring 34 is sleeved on the vertical rod of the exhaust valve 3 32. One end abuts against the projection 25 of the propeller 2, and the other end abuts against the side wing 33 of the exhaust valve 3. The elastic tension of the anti-leak spring 34 allows the exhaust valve 3 to initially position as the exhaust valve 3. The outer end 31 tightly abuts against the groove 221 outside the bottom end seat 22 of the thruster 2, and the outer end 31 of the exhaust valve 3 can close the exhaust passage 250 of the thruster 2, as shown in the ninth and Shown in ten pictures.

The aforementioned propeller 2 combined with the exhaust valve 3 can be accommodated in the aforementioned circular tube body 1 and the bottom end seat 22 abuts against the bottom of the inner chamber 11, the inner channel 140 of the connector 14 and the inner chamber 11 of the circular tube body 1 can be Communicate with each other so that the input pressure of the pressure source can be applied to the outer end 31 of the thruster 2 and the exhaust valve 3 through the inner passage 140 and the inner chamber 11 of the circular tube body 1, the thruster 2 and the thruster 2 The combined exhaust valve 3 can be linearly displaced in the inner chamber 11 between the left section 111 and the right section 112 of the circular pipe body 1 in a manner similar to the movement of a piston, as shown in the tenth to thirteenth figures.

An elastic element, such as a spring. The present invention uses a main spring 4, which can be accommodated in the inner hollow portion 23 of the aforementioned propeller 2 and is sheathed around the periphery of the hollow tube 24. One end of the main spring 4 is just right Abut the ring recess 26.

A cover body 5 is provided with a female thread 50 on its inner peripheral surface, a center seat 51 is provided at the center of the inner surface side of the cover body 5, a ring receiving groove 53 is formed between the center seat 51 and the inner side wall of the cover body 5, and the center seat A cross top pin 52 extends from the top of 51. The cross top pin 52 is a non-circular cylinder. The diameter is smaller than the outer diameter of the central base 51. An outer wall 511 is arranged at the joint between the cross pin 52 and the central base 51, and the joint between the outer wall 511 and the central base 51 forms a top wall 512, the outer surface of the cover 5 is provided with a plurality of output air passages 54 arranged in a ring shape. As shown in the eighth figure, the output air passages 54 are in communication with the annular receiving groove 53 of the cover 5, allowing the gas pressure to be changed from Here it flows out to the outside, as shown in the tenth to thirteenth pictures. When the cover body 5 is screwed to the male thread 121 of the open end 12 of the circular tube body 1 with its female thread 50, the two can be screwed and positioned. The state can be used to adjust the pressure value of the pressure gauge 10, the other end of the aforementioned main spring 4 is attached to the top platform 512 of the cover 5, and the inner diameter edge of the main spring 4 slightly abuts the expansion 511 outside the cover 5 Outer wall. After the round pipe body 1, the propeller combined with the exhaust valve 3, the colored O-ring 28, the air-tight O-ring 15, 16, the main spring 4 and the cover 5 are completely combined, the second and The pressure gauge 10 shown in the embodiment of the three figures.

Please refer to Figures 1 and 11. The external pressure source can enter the tube body 1 of the pressure gauge 10 through the inner channel 140 of the connector 14 of the tube body 1, and the input external pressure can force the thruster 2 to force the inside. The main spring 4, the continuous input of external pressure can push the pusher 2 combined with the exhaust valve 3 to the direction of the cover 5. The current pressure value can be used by the user from the transparent tube body 1. The number on the display unit 17 where the clear color O-ring 28 is located depicts the pressure value. As shown in the sixth figure, when the input pressure value is greater than the set safety pressure value, the periphery of the bottom end seat 22 of the thruster 2 When the colored O-ring 28 on the side moves across the first vent hole 18 provided on the outer cylinder wall of the left section 111 of the circular tube body 1, the excess pressure will immediately be released through the first vent hole 18 to release the pressure gauge 10, as shown in Figure 11, and the subsequent external pressure entering the pressure gauge 10 continues to push the pusher 2 combined with the exhaust valve 3 toward the cover 5, and the bottom end of the pusher 2 The colored O-ring 28 on the peripheral side of the seat 22 can just cross the ring section 113 by the small-caliber left section 111, so that the excess pressure follows the colored O-ring 28 and the ring section 113 on the propeller 2 The formed gap 114 enters the right section 112 in a full-circumference 360-degree pressure relief manner, and the excess pressure can simultaneously release the pressure gauge through the first vent hole 18 and the second vent hole 19 provided on the outer cylinder wall of the right section 112 10 outside, as shown in the twelfth figure. For the purpose of safety protection, when the displacement of the thruster 2 of the pressure gauge 10 reaches the maximum limit point, the exhaust valve 3 provided on the exhaust passage 250 at the end of the thruster 2 to close the exhaust passage 250 will be covered The cross pin 52 at the front end of the body 5 is moved and opened, so that the high-pressure air in the pressure gauge 10 will quickly enter the circular tube body 1 through the groove 221, the exhaust channel 250, the hollow tube 24, and the circulation groove 520 of the cross pin 52 The content chamber 11 and the ring receiving groove 53 of the cover body 5 vent the excess pressure through the output air passage 54 provided in the cover body 5 and the aforementioned first vent hole 18 and second vent hole 19, as shown in Figure 13 Show. On the other hand, when an overpressure phenomenon occurs due to improper operation during the inflation stage, the end of the hollow tube 24 of the thruster 2 can be used to abut the expansion wall 511 outside the cover 5. This design method can protect the main spring 4. The main spring 4 will not be deformed due to excessive pressure.

Please refer to FIG. 14, the inner surface of the display unit 17 with the numerically depicted pressure value is integrally formed with the circular tube body 1 to form a pressure gauge 10.

To sum up, the present invention provides a pressure gauge 10 with multi-stage safety pressure relief. The air delivery manifold set on the air storage seat of the air compressor 9 can be directly connected to a pressure with an overpressure protection unit. Gauge 10, when the thruster 2 of the pressure gauge 10 receives different input pressure values, when the input pressure value is greater than the set safe pressure value, the excess pressure will be immediately released out of the pressure gauge 10 through at least one vent hole, and When the thruster 2 of the pressure gauge 10 subsequently receives more input pressure values, the excess pressure will be released out of the pressure gauge 10 through at least two vent holes, and when the thruster 2 of the pressure gauge 10 travels to the maximum limit point , The exhaust valve 3 provided on the exhaust passage 250 at the end of the propeller 2 to close the exhaust passage 250 will be opened by the cross pin 52 at the front end of the cover 5, so that the high-pressure air in the pressure gauge 10 will It enters the propeller 2 through the exhaust passage 250, and then releases the excess pressure through the output air passage 54 provided in the cover 5 and the aforementioned vent hole, not only does not need to be installed on another air delivery manifold of the air compressor 9 In addition to a pressure safety valve, it can also protect the safety of the inflated object. The structure of the present invention is not only different from the existing conventional products, but also can measure the pressure value accurately and sensitively, which is quite practical. At the same time, the overpressure protection unit is used to prevent overpressure. The inflatable operation of this invention has a safety effect. The present invention is obviously novel and progressive, and it is a patent application.

10: Pressure gauge 1: Round tube body 11: content room 111: Left section 112: Right part 113: ring segment 114: gap 121: male thread 13: tail end 131: Inlay 14: Connector 140: inner channel 15: Airtight O-ring 16: Airtight O-ring 17: display unit 18: The first vent 19: second vent 21: open end 22: bottom end seat 221: Groove 23: Internal space 24: Hollow tube 25: Protruding Wall 250: exhaust channel 26: Ring cavity 27: ring groove 28: Colored O-ring 3: Exhaust valve 31: Outer end 32: Vertical pole 33: Flanking 34: anti-leak spring 4: main spring 5: Lid 50: Female thread 51: Center Block 511: Outer Expansion 512: Top Taiyuan 52: Cross top pin 520: Circulation Slot 53: ring groove 54: output airway C: central axis X: radius Y: radius 9: Air compressor

The first figure: is a perspective view of the pressure gauge of the present invention assembled in an air compressor. The second figure: is a three-dimensional view of the pressure gauge of the present invention. Figure 3: An exploded view of the pressure gauge of the present invention. The fourth figure: is a plane cross-sectional view of the round tube body of the present invention. Figure 5: is a three-dimensional cross-sectional view of the thruster of the pressure gauge of the present invention. Figure 6: The top view of the pressure gauge of the present invention. Figure 7: is a bottom view of the pressure gauge of the present invention. Figure 8: It is a rear view of the pressure gauge of the present invention. Figure ninth: is a cross-sectional plan view of the combination of the exhaust valve and the propeller of the present invention. Figure 10: is a schematic plan view of the pressure gauge of the present invention in the zero pressure initial state. Figure 11: is a cross-sectional schematic diagram of the pressure gauge of the present invention receiving the pressure source and the thruster performing piston-like motion. Figure 12: is a schematic diagram of the pressure gauge of the present invention when the excess pressure is being deflated. Figure 13: It is a schematic diagram of the deflation action when the pressure gauge of the present invention receives a pressure source, and the thruster performs a piston-like motion and displaces to the maximum limit point. Figure 14: is a diagram of another embodiment of the pressure gauge of the present invention.

10: Pressure gauge

1: Round tube body

12: open end

121: male thread

13: tail end

131: Inlay

14: Connector

140: inner channel

15: Airtight O-ring

16: Airtight O-ring

17: display unit

2: thruster

21: open end

22: bottom end seat

221: Groove

24: Hollow tube

25: Protruding Wall

250: exhaust channel

27: ring groove

28: Colored O-ring

3: Exhaust valve

31: Outer end

32: Vertical pole

33: Flanking

34: anti-leak spring

4: main spring

5: Lid

50: Female thread

52: Cross top pin

520: Circulation Slot

Claims (7)

A pressure gauge with multi-stage safety pressure relief. The pressure gauge includes: a hollow round tube body, the hollow round tube body is a transparent cylindrical body with an inner chamber, and the center of the outer end of the tube body is additionally provided There is a connector with an internal channel communicating with the content chamber of the circular tube body. The circular tube body is provided with a display unit combined with a digital depiction of the pressure value on the outer side near the tail end. The circular tube system is formed in the content chamber with two There are two left and right sections with different circular calibers, a radial ring section is formed between the left section and the right section, and at least one vent is provided on the outer cylinder wall of the circular tube body Hole; a propeller provided with an overpressure protection unit, which can be placed in the aforementioned circular tube body, when the compressed air generated by the air compressor enters the aforementioned circular tube body, in addition to pushing the overpressure protection unit provided In addition to the linear displacement of the thruster, the current pressure value is also indicated by the length of the thruster’s movement. The thruster has an open end at one end, and the other end is a bottom end seat. There is an inner hollow part, the bottom end seat extends at the center of the bottom of the inner hollow part, a hollow tube extending through the open end, and a protrusion with an exhaust passage is arranged inside the hollow tube of the bottom end seat Wall; a leak-proof spring, which can be placed in the hollow tube of the thruster, and one end of the leak-proof spring is attached to the convex wall, and the other end is against the overpressure protection unit; an elastic element, which can be accommodated in the aforementioned thruster The inner hollow part is covered and surrounds the periphery of the hollow tube; a cover body, a center seat is provided at the center of the inner surface of the cover body, and a cross top pin extends from the top of the center seat, the cross top pin is A non-circular cylinder, the outer surface of the cover is provided with a plurality of annularly arranged output air passages, and the other end of the aforementioned elastic element is attached to the cover; with the above structure, the compressed air generated by the air compressor passes through The inner channel of the connector can enter the body of the round tube. When the thruster equipped with the overpressure protection unit is subjected to different input pressure values, when the input pressure value exceeds the set safety pressure value, the excess pressure will immediately pass through at least A vent is released from the pressure gauge, and when the thruster provided with the overpressure protection unit travels to the maximum limit point, the exhaust passage at the end of the thruster is set to close the overpressure of the exhaust passage The protection unit will be opened by the cross pin at the front end of the cover, so that the high-pressure air in the pressure gauge will enter the inner chamber of the round tube through the exhaust channel and hollow tube, and then through the output air passage set by the cover and the aforementioned vent The hole discharges excess pressure. For example, the pressure gauge with multi-stage safety pressure relief described in the first item of the scope of patent application, wherein one end of the round tube body is an open end and is provided with a male thread, and the other end is the aforementioned tail end and is provided with a pair of insert clamping bodies, Two separate gas-tight O-rings are installed on the connecting head; based on the central axis C of the circular tube body, the left section with a radius X near the inner channel, and the adjacent open end It has a right section with a radius of Y, and the radius X is smaller than the radius Y (X>Y). At the ends of the left and right sections adjacent to each other, a radial shape is formed inside the circular tube. The ring section with a slope (relative to the central axis C) is provided with a first vent hole on the outer tube wall of the left section near the ring section, and at the right section near the ring section The outer cylindrical wall of the round tube of the part is provided with a second vent hole. For example, the pressure gauge with multi-stage safety pressure relief described in item 2 of the scope of patent application, wherein the thruster is provided with a recessed groove on the outer plane of the bottom end seat, and the grooves and rows on the outside of the bottom end seat The air channel and the hollow tube are in a connected state, and a ring recess is formed between the bottom of the hollow tube of the thruster and the cylinder wall of the thruster. A ring recess is provided on the peripheral side of the bottom end seat, and a colored O can be sleeved in it. Type ring. As described in item 3 of the scope of patent application, the pressure gauge with multi-stage safety pressure relief, wherein the overpressure protection unit is an exhaust valve, which is provided with an outer end, and the other end of the outer end is extended There is a vertical rod, the end of the vertical rod is equipped with two opposite side wings; the side wing end of the aforementioned exhaust valve is penetrated into the exhaust channel and the anti-leak spring from the groove on the outside of the bottom end seat of the propeller, and the exhaust The flank of the valve is hooked to the other end of the anti-leak spring, and the outer end of the exhaust valve is seated in the groove outside the bottom end seat of the propeller. At this time, the anti-leak spring is sleeved on the exhaust valve. One end of the vertical rod is against the protruding wall of the propeller, and the other end is against the side wing of the exhaust valve. The elastic tension of the anti-leak spring can make the initial position of the exhaust valve close to the outer end of the exhaust valve. The outer end of the exhaust valve can close the exhaust channel of the thruster by touching the groove on the outer side of the bottom end seat of the thruster. As described in the third item of the scope of patent application, the pressure gauge with multi-stage safety pressure relief, wherein the aforementioned elastic element is a main spring, one end of the main spring can abut against the ring cavity of the propeller. As described in item 5 of the scope of patent application, the pressure gauge with multi-section safety pressure relief, wherein the inner peripheral surface of the cover body is provided with a female thread, and a ring receiving groove is formed between the center seat of the cover body and the side wall of the cover body, and the cover body The outer peripheral surface of the cross top pin has an inwardly recessed circulation groove. The outer diameter of the cross top pin is smaller than the outer diameter of the center seat. An outer wall is provided at the junction between the cross top pin and the center seat. , And the junction between the outer expansion wall and the central seat forms a top platform. The aforementioned output airway is in communication with the ring groove of the cover, allowing gas pressure to flow out from here to the outside; when the cover is exposed to its shadow The thread is screwed to the male thread of the open end of the tube body, so that the two can be screwed and positioned. The depth of the threading of the tube body and the cover body can be used to adjust the pressure value of the pressure gauge. The aforementioned main spring The other end is tied to the top platform of the cover body, and the inner diameter edge of the main spring slightly abuts against the outer wall of the expansion wall outside the cover body. The pressure gauge with multi-stage safety pressure relief described in the first item of the scope of patent application, wherein the inner side of the display unit with the numerically depicted pressure value is combined with the circular tube body separately or integrally to form a pressure gauge.

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